<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>

</body>


<script>


    let price=100;
    let str=`这件毛衣值${price}元`;
    document.write(str);

</script>

<script>
    let s="abcdefg";
    console.log(s.substr(2, 3));
    console.log(s.substring(2, 3));


</script>

</html>